The ancient river of Patalganga and small streams flow through the area.

This is particularly evidenced by remnants of ancient rivers found throughout the country.

It is one of the well preserved ancient Philippine rivers.

"The ancient river probably went underground at this point."

The ensemble is named for an ancient river of the Pisan region.

But if so, when and how were those ancient rivers formed and where did they go?

Just beyond the town, the ancient, brackish river looked like flowing iron.

Water was available through freshwater springs and an ancient river.

The ancient river had left a legacy, for there was still moisture along the lower reaches of the valley.

The park's flat prairie area is a terrace of the ancient river.